Piston anomoly

[cowlum]

I just cant seem to change the amount of fluid sitting on top of the piston. If I heat the engine up fully, then remove the spark plug it doesn't boil or evaporate despite the heat. Leads me to believe its oil rather than coolant. So I'm less worried. I'll let it sit a few days with plugs out and see if its evaporates. Another thing I did this afternoon was fill the tank with fresh stuff but I doubt the 10-15 minutes run time was long enough to get fresh stuff through the filter and into the engine. The tank was extremely low.

I'll still pressure test the block and manifold when I collect all the required part. I'm curious to try this anyway and it will completely settle what happens next.

Thanks

[romantic comedy]

I just cant seem to change the amount of fluid sitting on top of the piston. If I heat the engine up fully, then remove the spark plug it doesn't boil or evaporate despite the heat. Leads me to believe its oil rather than coolant. So I'm less worried. I'll let it sit a few days with plugs out and see if its evaporates. Another thing I did this afternoon was fill the tank with fresh stuff but I doubt the 10-15 minutes run time was long enough to get fresh stuff through the filter and into the engine. The tank was extremely low.

I'll still pressure test the block and manifold when I collect all the required part. I'm curious to try this anyway and it will completely settle what happens next.

Thanks

Maybe you could add some oil to the cylinder. If it is water they wont mix and you should be able to tell. Maybe there is something better to add?

[Dave Neptune]

The fluid looks like antifreeze. Is the engine raw water or fresh water cooled? The antifreeze will evaporate very slowly. Any running of the engine if it were oil would produce copious amounts of smoke once started, did it?

Dave Neptune

[cowlum]

Maybe you could add some oil to the cylinder. If it is water they wont mix and you should be able to tell. Maybe there is something better to add?

That’s a good idea, I’ll do that but ultimately aim for a pressure test.

[cowlum]

The fluid looks like antifreeze. Is the engine raw water or fresh water cooled? The antifreeze will evaporate very slowly. Any running of the engine if it were oil would produce copious amounts of smoke once started, did it?

Dave Neptune

It does look like that but after 15 minutes of running in gear, too hot to touch it looks exactly the same. Water in the exhaust is steaming the usual amount.

[ndutton]

Please address this question:

Is the engine raw water or fresh water cooled?

[cowlum]

Please address this question:

Fresh water cooled. No obvious coolant loss.
I'm not ruling out the idea its water, im just confused as to why it wont turn to steam. I guess my assumption was oils harder to burn than water is to steam. But maybe I assume too much.

My best guess at the moment its just something in the fuel that's not significantly effecting the way it runs... I need to get the pressure test parts and the time to test it.

[Peter]

It does look like that but after 15 minutes of running in gear, too hot to touch it looks exactly the same. Water in the exhaust is steaming the usual amount.

And is it possible that the usual amount of steam for your engine is consistent with a cooling leak somewhere?

My engine does not "steam" from the exhaust.

Just a suggestion.

Peter

PS - sort of like when I loaned my car to someone and half-way through explaining that the hockey stick through the hole in the floor is the brakes, I realized that maybe there IS something wrong with the car that should get fixed and that hockey stick brakes, while they were normal for me, are in fact not normal.

[JOHN COOKSON]

The fluid looks like antifreeze.
Dave Neptune

Agree, it is antifreeze. Not water. If it were water it would
'burn off" - assuming the engine would start with that much water in the cylinders.
I'm going to go against prevailing opinion and suggest that a compression would give some actionable information. The head gasket may be compromised some how some way.

ex TRUE GRIT

[cowlum]

Thanks guys

First things first. I will preform the pressure test when I get parts and my newborn allows the time, im not using the boat now anyway . Its result will decide what happens next and is all that really matters.

But I'm finding the speculation enjoyable non the less so to continue....

I did a few compression tests about a month ago, 95 on all cylinders and 90 for #4 on my original tester. Its been this every year since I bought the boat in 2013 with 200 hours on the engine since. Slightly higher across all four on the tester that came with the timing light kit a friend loaned me. I poured engine oil in cylinder 4 a month ago to see if it would raise compression in alignment with the others, it did not.

I also used seafaom cleaner about a month ago.

The steam from my exhaust is normal for the PNW at this time of year. All boats here steam. I've blown head gaskets on project cars in the past and a good amount of steam requires a good amount of radiator water. But yes, I agree the headgasket steam may be hidden in the normal PNW steam.

My doubts as it to it being water or antifreeze is even when the engines very hot it remains, not steaming, not bubbling. The exhaust port is peppered in white ash which is inline with heat and burning oil. Oil has a much higher flash point than water or antifreeze ive learnt since yesterday. So im still hopeful its just the oil from the compression test.

On the flip side I doubt oil cleans cylinders and pistions, this piston looks steam cleaned.
So this points to head gasket.

The engine runs perfectly and I would not have even been worried had I not put my borrowscope into the spark plug holes for curiosities sake... Lesson learned... or issue found early

The pressure test will reveal all.,,, hopefully.

thanks

[tenders]

PS - sort of like when I loaned my car to someone and half-way through explaining that the hockey stick through the hole in the floor is the brakes, I realized that maybe there IS something wrong with the car that should get fixed and that hockey stick brakes, while they were normal for me, are in fact not normal.

Wow, that is VERY Canadian.

[Peter]

sorry...

[cowlum]

Hi again

Today was sunny and we ended up going on a last minute cruise. I ran the engine for an hour, all running perfectly. My partner allowed me 20 minutes after to play with the engine while the kid slept.

So I decided to test some of my assumptions.

After running the engine for an hour on our cruise I poured a little antifreeze in cylinder 3 and a little engine oil in cylinder 4 after. The antifreeze did not boil as I had assumed, but it did not mix with the fluid on the surface of the piston. The oil mixed straight in.

This test lead me to believe the engine simple doesn't produce the heat to burn the motor oil. So I ran the engine at WOT for 30 seconds which produced the heat to brown the oil on the surface (i think).

Of interest, cylinder 3's spark plug and exhaust valve had been 'cleaned' by the antifreeze. cylinder 4's spark plug is still charcoal black.
I also tested antifreeze in C4 but dont have a good photo, it didnt mix same as cylinder 3.

I now think what I took a picture of in C4 a week ago was a piston cleaned by seafoam, which received the lions share due to gravitiy. Then covered in oil from the compression test.
That or it came in with the fuel with c4 getting the lions share due to gravity again.

My learning from these experiment is its not as hot inside the cylinder as I had originally assumed.
I also set up a antifreeze evaporation test.

Yes, Ill still be performing the pressure test sometime in the next month but thought maybe someone finds this as interesting as I do.